The main opposition Democratic Party and two minor progressive parties submitted a joint request Wednesday for a parliamentary investigation into the Itaewon crowd crush despite opposition from the ruling party.

The DP, the Justice Party (JP) and the Basic Income Party submitted the request to the National Assembly's Bills Division on Wednesday afternoon, with an aim to have the request reported at a parliamentary plenary session scheduled for Thursday.

"We should clearly determine where the responsibility lies and come up with measures to prevent a recurrence by looking thoroughly into the accident, including its cause and measures taken before or after the tragedy," the parties said in the request sponsored by 181 lawmakers.

The parties called for forming an 18-member special committee to oversee the probe and look into whether measures by government agencies were appropriate and whether there were attempts to minimize or cover up the tragedy.

Once the request is reported at a plenary session, the National Assembly speaker can form a special committee in charge of a probe through discussions with party leaders. The committee is then required to come up with an investigation plan that should be approved at a plenary session.

The three parties plan to approve the investigation plan on Nov. 24.

Opposition parties have been pushing to launch the parliamentary investigation, accusing the government of mishandling the tragedy following revelations that the police snubbed a series of emergency calls warning against overcrowding in Itaewon that day.

The crowd surge killed at least 156 Halloween partygoers in Seoul's entertainment district of Itaewon on Oct. 29, marking the nation's worst disaster since the 2014 Sewol ferry sinking that killed 304 people, mostly high school students.

The DP again urged the ruling People Power Party (PPP) to take part in the parliamentary probe but hinted at pushing ahead without its consent in the case the PPP does not budge.

"We will call on the ruling party to participate, but if it continues to reject, we cannot help but follow procedures written in law," DP floor leader Park Hong-keun said. "We cannot just wait when the people and victims are demanding it."

"Boycotting the parliamentary probe is equivalent to boycotting the people and the truth," Park said, pressing the ruling party.

The People Power Party reaffirmed its earlier rejection of the parliamentary probe, claiming a parliamentary probe should come after ongoing investigations.

"We believe that a swift compulsory investigation should be the principle and is the most effective means. Our stance is that a legally unbinding parliamentary probe only hinders ongoing probes and prompts political strife," PPP floor leader Joo Ho-young said.

"A parliamentary probe should be conducted in the case there are shortfalls with ongoing probes. Since they are smoothly proceeding, there seem to be motivations in proposing a parliamentary probe now."

The presidential office advised against exploiting the tragedy for political gain.

"The people will judge what was behind the Itaewon accident," a presidential official told reporters, saying the office will wait and see the results of an ongoing police investigation into the circumstances that led to the disaster. "This sadness should not be used for politics."

Later in the day, the PPP leadership visited the site of the Itaewon tragedy for the first time since it happened and paid respects to the victims at a nearby mourning altar.

The PPP leaders had not visited the site until Wednesday saying their visit could hamper efforts to deal with the accident.

"We only have a sense of embarrassment and sorrow ... we will bury the sadness and regret in our hearts and promise to make South Korea safer," PPP's interim chief Chung Jin-suk wrote in a memorial book.

Chung also told police and fire officers at the scene that the ongoing investigation is intended to clarify where responsibility lies, not to blame police and fire authorities.

Some observers have accused the government of trying to hold field officials accountable over the Itaewon disaster to protect high-level officials who should have been in charge.

Meanwhile, Yoon Hee-keun, commissioner general of the National Police Agency, told reporters he will keep his position until the truth comes out, saying stepping down is actually a "cowardly act."

"My role is to keep this position while enduring all the criticism to uncover the truth, deal with the accident and devise necessary measures," Yoon said, adding he will decide whether to step down after the case is wrapped up. (Yonhap)